A three-phase single-stage conversion circuit, power supply device, vehicle, and control method

Abstract

This invention provides a three-phase single-stage converter circuit, power supply equipment, vehicle, and control method. It includes three primary-side bridge modules, three transformers, and a secondary-side half-bridge module. Each secondary-side half-bridge module comprises three secondary-side half-bridge arms and a common half-bridge arm. The first end of the secondary winding of each transformer is connected to the midpoint of one of the secondary-side half-bridge arms, and the second end of each secondary-side winding is connected to the midpoint of the common half-bridge arm. The high-ends of the three secondary-side half-bridge arms are connected to the high-ends of the common half-bridge arm, and the low-ends of the three secondary-side half-bridge arms are connected to the low-ends of the common half-bridge arm. By designing the secondary side of the three-phase converter circuit as a shared structure of three independent half-bridge arms and one common half-bridge arm, the number of switching transistors is significantly reduced, greatly simplifying the PCB layout and drive circuit design, and effectively improving the system's power density and reliability.

Description

Technical Field

[0001] This invention relates to the field of power supply equipment technology, and in particular to a three-phase single-stage conversion circuit, power supply equipment, vehicle, and control method. Background Technology

[0002] Traditional high-power AC-DC isolated converters typically employ a two-stage structure: the front stage uses a non-isolated power factor correction circuit to correct the power factor at the AC input to meet grid harmonic and power factor requirements; the rear stage uses a transformer-isolated DC-DC converter circuit, such as LLC or DAB topologies, to achieve precise control of the output voltage and current. The two stages are connected via a DC bus, with a large-capacity electrolytic capacitor connected in parallel on this bus for energy smoothing and filtering.

[0003] In recent years, with the rapid development of the new energy vehicle industry, the requirements for reliability, efficiency, cost, and power density of on-board charging systems and charging piles have been increasing. The traditional two-stage converter structure is gradually becoming unable to fully meet these demands. Its limitations are mainly reflected in the following aspects: First, each stage of power conversion introduces certain losses, making it difficult to further improve the overall system efficiency; second, the number of components used is relatively large, resulting in higher system costs and larger size; in addition, the intermediate DC bus must rely on large-capacity electrolytic capacitors, which have a short lifespan, becoming a weak link affecting the long-term reliability of the system.

[0004] To address the aforementioned challenges, single-stage converter circuits without electrolytic capacitors have begun to be used in new energy vehicle charging systems. This type of topology, through a single power conversion stage, can simultaneously achieve power factor correction at the AC input and voltage and current control at the DC port, demonstrating significant potential in terms of structural simplification, efficiency improvement, and reliability enhancement. Currently, matrix converter circuits employing bidirectional GaN devices or other bidirectional switches have become the mainstream single-stage converter scheme in new energy vehicle charging systems, offering advantages such as simple structure, high efficiency, and low cost. A typical single-phase, single-stage matrix converter circuit is shown below. Figure 1 As shown, where Figure 1 'a' represents a primary-side full-bridge and secondary-side full-bridge topology, suitable for high-power applications. Figure 1 Topology b is a primary-side half-bridge plus a secondary-side full-bridge, which is commonly seen in applications with lower power ratings. Although theoretically, the primary-side half-bridge plus secondary-side half-bridge structure can also be used for single-phase single-stage conversion, it is rarely used in practice due to its lower degree of control freedom and poor performance.

[0005] For three-phase single-stage converter circuits, since on-board charging systems need to be compatible with both single-phase and three-phase inputs, general three-phase topologies are difficult to apply directly. Currently, the industry commonly uses a method of combining three independent single-phase single-stage converter circuits into a three-phase system: with three-phase input, each phase input is connected to a separate converter; with single-phase input, the input terminals of the three converters are connected in parallel to the same phase line. The mainstream power of three-phase on-board charging systems is around 11kW, with each phase handling approximately 3.3kW, which is considered medium power. Therefore, a primary-side half-bridge plus a secondary-side full-bridge topology is often used to save on the number of switching devices and simplify the circuit structure, such as... Figure 2 As shown. If higher power requirements are needed, a topology consisting of a primary-side full-bridge and a secondary-side full-bridge can also be selected.

[0006] However, Figure 2 The existing three-phase single-stage matrix converter circuit shown still suffers from an excessive number of switching devices: each phase requires 6 switching transistors, totaling 18 for all three phases. This excessive number of switching transistors not only occupies a large layout area, but each transistor also requires its own independent drive circuit and even an isolated power supply, leading to a complex overall circuit structure, increased cost, and hindering system compactness and high reliability design. Summary of the Invention

[0007] The primary objective of this invention is to provide a simplified three-phase single-stage converter circuit.

[0008] A second objective of this invention is to provide a power supply device having the above-described three-phase single-stage conversion circuit.

[0009] A third objective of this invention is to provide a vehicle having the aforementioned three-phase single-stage conversion circuit.

[0010] The fourth objective of this invention is to provide a control method applicable to the above-mentioned three-phase single-stage converter circuit.

[0011] To achieve the first objective of this invention, a three-phase single-stage converter circuit is provided, comprising three primary-side bridge modules, three transformers, and a secondary-side half-bridge module. The midpoint of the arm of each primary-side bridge module is connected to the primary winding of a transformer, the high-end of the arm of each primary-side bridge module is connected to the live wire of the AC power supply, and the low-end of the arm of each primary-side bridge module is connected to the neutral wire of the AC power supply. The secondary-side half-bridge module comprises three secondary-side half-bridge arms and a common half-bridge arm. The first end of the secondary winding of each transformer is connected to the midpoint of the arm of a secondary-side half-bridge arm, and the second end of the secondary winding of each transformer is connected to the midpoint of the arm of the common half-bridge arm. The high-ends of the three secondary-side half-bridge arms are connected to the high-ends of the common half-bridge arm, and the low-ends of the three secondary-side half-bridge arms are connected to the low-ends of the common half-bridge arm.

[0012] As can be seen from the above, by designing the secondary side of the three-phase converter circuit as a shared structure of three independent half-bridge arms and one common half-bridge arm, the number of switching transistors is significantly reduced. This not only directly reduces the cost of components, but also greatly simplifies the PCB layout and drive circuit design, effectively improving the power density and reliability of the system, and achieving the core objective of simplifying the circuit structure.

[0013] A further proposed solution is to replace the primary-side bridge module with a primary-side half-bridge module.

[0014] As can be seen from the above, using a primary-side half-bridge module is the preferred solution that balances performance and cost. For mainstream medium-power applications such as vehicle charging, the half-bridge structure can minimize the number of expensive bidirectional switching devices on the primary side while ensuring power transmission capability. Each phase can use two switching transistors, further effectively controlling the cost of the circuit and simplifying the circuit structure.

[0015] A further proposed solution is that the primary-side half-bridge module includes a primary-side upper switch, a primary-side lower switch, an upper voltage divider capacitor, and a lower voltage divider capacitor. The primary-side upper switch and the primary-side lower switch are connected in series to form the primary-side half-bridge arm, and the upper voltage divider capacitor and the lower voltage divider capacitor are connected in series to form a voltage divider branch. The voltage divider branch is connected in parallel with the primary-side half-bridge arm.

[0016] As can be seen from the above, the bridge arm composed of switching transistors and the parallel voltage divider branch composed of capacitors together establish a stable and reliable high-frequency operating platform for the primary winding of the transformer. The introduction of the voltage divider capacitor is particularly crucial in providing a stable midpoint potential for the bridge arm, ensuring effective power transmission and safe operation of the converter.

[0017] A further proposed solution is to connect the high end of the primary half-bridge arm to the live wire of the AC power supply, the low end of the primary half-bridge arm to the neutral wire of the AC power supply, the midpoint of the primary half-bridge arm to the first end of the primary winding of the transformer, and the midpoint of the voltage divider branch to the second end of the primary winding of the transformer.

[0018] As can be seen from the above, the electrical interface between the primary half-bridge module and the external AC power supply and transformer can ensure the optimization of the high-frequency switching current path, so that the AC input power can be efficiently and controllably transferred to the isolation transformer, which is the physical basis for realizing single-stage power factor correction and voltage transformation.

[0019] A further proposed solution is to include a buffer capacitor in the primary-side half-bridge module, which is connected in parallel with the primary-side half-bridge arm.

[0020] As can be seen from the above, by adding a buffer capacitor, the voltage spike generated by the primary-side switching transistor during high-speed turn-off can be effectively suppressed, protecting the switching device that is sensitive to voltage stress. At the same time, it helps to achieve zero-voltage switching, thereby significantly reducing switching losses and improving the overall efficiency and electromagnetic compatibility.

[0021] A further proposed solution is that the secondary half-bridge module includes an output filter capacitor, and the common half-bridge arm is connected in parallel with the output filter capacitor.

[0022] As can be seen from the above, setting an output filter capacitor at the secondary DC output terminal can effectively filter out the switching frequency ripple after rectification, provide a smooth and stable DC voltage for the load, ensure the quality of the output voltage, and meet the stringent load requirements.

[0023] A further proposed solution is to locate the primary resonant inductance of the transformer on one side of the primary winding.

[0024] As can be seen from the above, placing the resonant inductor on the primary side of the transformer facilitates its integration or collaborative design with the primary leakage inductance of the transformer, thereby reducing the overall size of the magnetic components.

[0025] A further proposed solution is to locate the secondary resonant inductance of the transformer on one side of the secondary winding.

[0026] As can be seen from the above, placing the resonant inductor on the secondary side of the transformer allows for its integration and coordinated design with the leakage inductance of the secondary side of the transformer, further reducing the overall size of the magnetic core device.

[0027] A further proposed solution is a three-phase single-stage converter circuit that includes a DC blocking capacitor connected between the secondary winding of the transformer and the midpoint of the secondary half-bridge arm.

[0028] As can be seen from the above, by adding a DC blocking capacitor, it can block the DC component that may be generated due to asymmetric control pulse width or differences in device parameters from flowing into the secondary winding of the transformer, fundamentally preventing DC bias saturation of the transformer core and ensuring the safety and stability of the converter in long-term operation.

[0029] A further approach is to use bidirectional gallium nitride (GaN) switching devices for the primary-side upper and / or lower primary-side switching transistors.

[0030] As can be seen from the above, bidirectional gallium nitride (GaN) switching devices have characteristics such as high frequency, low conduction loss, and fast switching, which enable the present invention to achieve bidirectional conduction capability. This allows the circuit to operate at higher frequencies, thereby reducing the size of passive components and fully leveraging the potential of the phase-shift control algorithm to achieve extremely high conversion efficiency and power density.

[0031] A further proposed solution is that the three-phase single-stage converter circuit also includes an input switching circuit, which is connected between the primary half-bridge module and the live wire of the AC power supply. The input switching circuit is configured to either a three-phase input mode or a single-phase input mode. In the three-phase input mode, the high-end arms of the three primary half-bridge modules are respectively connected to three different live wires of the three-phase AC power supply. In the single-phase input mode, the high-end arms of the three primary half-bridge modules are connected together to the same live wire of the single-phase AC power supply.

[0032] As can be seen from the above, by introducing an input switching circuit, this invention cleverly solves the problem of compatibility with single-phase and three-phase power grids. By simply changing the state of the switching circuit, the same hardware platform can adapt to different input power supplies, greatly improving the product's versatility and user convenience.

[0033] A further embodiment includes an input switching circuit comprising at least one single-pole double-throw relay, the moving end of which is connected to the high end of the bridge arm of at least one primary-side half-bridge module; the first stationary end of the single-pole double-throw relay is configured to connect to the corresponding live wire of the three-phase AC power supply in three-phase input mode; the second stationary end of the single-pole double-throw relay is configured to connect to the same live wire of the single-phase AC power supply together with the high end of the bridge arm of the remaining primary-side half-bridge modules in single-phase input mode.

[0034] As can be seen from the above, using a single-pole double-throw relay is a reliable, low-cost, and easy-to-control preferred solution for realizing the above input switching function. By utilizing the mechanical switching of relay contacts, the input network can be reconfigured, ensuring electrical isolation and connection reliability in the two working modes, and the circuit implementation is simple and effective.

[0035] To achieve the second objective of this invention, this invention provides a power supply device including the three-phase single-stage conversion circuit described above.

[0036] As can be seen from the above, the power supply device integrating the three-phase single-stage conversion circuit of the present invention benefits from the significant advantages of its circuit in terms of simplified structure, improved efficiency and enhanced reliability. The power supply device achieves higher power density and lower manufacturing cost by reducing the number of switching transistors and drive circuits.

[0037] To achieve the third objective of this invention, this invention provides a means of transportation that includes the three-phase single-stage conversion circuit described above.

[0038] As can be seen from the above, applying the three-phase single-stage conversion circuit of this invention to the on-board charging system or other power supply units of vehicles can directly meet the core requirements of vehicles for lightweight, compact, efficient and highly reliable power supply components. Its simplified circuit structure helps to reduce size and weight and improve space utilization. Its high efficiency helps to extend the driving range. Its high reliability design ensures long-term stable operation in the complex operating environment of vehicles, thereby improving the electrical system performance and market competitiveness of vehicles.

[0039] To achieve the fourth objective of this invention, this invention provides a control method for a three-phase single-stage converter circuit applied to the above-described scheme; The first primary-side half-bridge module includes a primary-side upper switch Q11 and a primary-side lower switch Q12. The primary-side upper switch Q11 and the primary-side lower switch Q12 are connected in series to form the first primary-side half-bridge arm. The primary-side upper switch Q11 and the primary-side lower switch Q12 are complementary in conducting with a 50% duty cycle. The second primary-side half-bridge module includes primary-side upper switch Q21 and primary-side lower switch Q22. The primary-side upper switch Q21 and primary-side lower switch Q22 are connected in series to form the second primary-side half-bridge arm. The primary-side upper switch Q21 and primary-side lower switch Q22 are complementary in conducting with a 50% duty cycle. The third primary-side half-bridge module includes primary-side upper switch Q31 and primary-side lower switch Q32. The primary-side upper switch Q31 and primary-side lower switch Q32 are connected in series to form the third primary-side half-bridge arm. The primary-side upper switch Q31 and primary-side lower switch Q32 are complementary in conducting with a 50% duty cycle. The first secondary half-bridge arm includes a secondary upper switch Q15 and a secondary lower switch Q16. The secondary upper switch Q15 and the secondary lower switch Q16 are connected in series to form the first secondary half-bridge arm. The secondary upper switch Q15 and the secondary lower switch Q16 are complementary in conducting with a 50% duty cycle. The second secondary half-bridge arm includes an upper secondary switch Q25 and a lower secondary switch Q26. The upper secondary switch Q25 and the lower secondary switch Q26 are connected in series to form the second secondary half-bridge arm. The upper secondary switch Q25 and the lower secondary switch Q26 are complementary in conducting with a 50% duty cycle. The third secondary half-bridge arm includes the upper secondary switch Q35 and the lower secondary switch Q36. The upper secondary switch Q35 and the lower secondary switch Q36 are connected in series to form the third secondary half-bridge arm. The upper secondary switch Q35 and the lower secondary switch Q36 are complementary in conducting with a 50% duty cycle. The common half-bridge arm includes a common upper switch Q7 and a common lower switch Q8. The common upper switch Q7 and the common lower switch Q8 are connected in series to form a common secondary side arm. The common upper switch Q7 and the common lower switch Q8 are complementary in conduction with a 50% duty cycle. There is a phase difference φ1 between the common upper switch Q7 and the primary side upper switch Q11, and a phase difference α1 between the common upper switch Q7 and the secondary side lower switch Q16; There is a phase difference φ2 between the common upper switch Q7 and the primary side upper switch Q21, and a phase difference α2 between the common upper switch Q7 and the secondary side lower switch Q26; There is a phase difference φ3 between the common upper switch Q7 and the primary side upper switch Q31, and a phase difference α3 between the common upper switch Q7 and the secondary side lower switch Q36.

[0040] As can be seen above, by independently setting the outward phase shift angle (φ) and inward phase shift angle (α) based on the common bridge arm signal for each phase, the power factor at the input end and the current at the output end of that phase can be precisely controlled simultaneously. Although the three-phase secondary sides share a bridge arm in hardware, thanks to this decoupling control strategy, the three phases can achieve completely independent power regulation without interference. Thus, on the basis of simplifying the hardware, the flexible and precise control performance of the independent three-way converter can also be obtained. Attached Figure Description

[0041] Figure 1 This is a circuit diagram of a single-phase, single-level matrix converter circuit in the prior art.

[0042] Figure 2 This is a circuit diagram of a three-phase input single-stage matrix converter circuit in the prior art.

[0043] Figure 3 This is a circuit diagram of an embodiment of the three-phase single-stage converter circuit of the present invention.

[0044] Figure 4 This is a timing diagram of the drive signals of the switching transistors in an embodiment of the control method for the three-phase single-stage converter circuit of the present invention.

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0046] Example of a three-phase single-stage converter circuit: Reference Figure 3 and Figure 4 The three-phase single-stage converter circuit includes three primary-side bridge modules, three transformers, and a secondary-side half-bridge module. The midpoint of the bridge arm of each primary-side bridge module is connected to the primary winding of a transformer. The high end of the bridge arm of each primary-side bridge module is connected to the live wire of the AC power supply, and the low end of the bridge arm of each primary-side bridge module is connected to the neutral wire of the AC power supply. In this embodiment, the primary-side bridge module is a primary-side half-bridge module. Each primary-side half-bridge module includes an upper primary-side switch, a lower primary-side switch, an upper voltage divider capacitor, a lower voltage divider capacitor, and a buffer capacitor. The upper and lower primary-side switches are connected in series to form a primary-side half-bridge arm. The upper and lower voltage divider capacitors are connected in series to form a voltage divider branch, which is connected in parallel with the primary-side half-bridge arm. The high end of the primary-side half-bridge arm is connected to the live wire of the AC power supply, the low end of the primary-side half-bridge arm is connected to the neutral wire of the AC power supply, the midpoint of the primary-side half-bridge arm is connected to the first end of the primary winding of the transformer, the midpoint of the voltage divider branch is connected to the second end of the primary winding of the transformer, and the buffer capacitor is connected in parallel with the primary-side half-bridge arm.

[0047] Specifically, the first primary-side half-bridge module includes an upper primary-side switch Q11, a lower primary-side switch Q12, an upper voltage divider capacitor C11, a lower voltage divider capacitor C12, and a buffer capacitor C1. The upper primary-side switch Q11 and the lower primary-side switch Q12 are connected in series to form the first primary-side half-bridge arm. The upper primary-side switch Q11 and the lower primary-side switch Q12 are complementary in conduction with a 50% duty cycle. The upper voltage divider capacitor C11 and the lower voltage divider capacitor C12 are connected in series to form the first voltage divider branch. A voltage divider branch is connected in parallel with the first primary half-bridge arm. The high end of the primary half-bridge arm is connected to the AC power live wire terminal L1, the low end of the first primary half-bridge arm is connected to the AC power neutral wire terminal N, the midpoint of the first primary half-bridge arm is connected to the first end of the primary winding of transformer Tr1, the midpoint of the first voltage divider branch is connected to the second end of the primary winding of transformer Tr1, and the buffer capacitor C1 is connected in parallel with the first primary half-bridge arm.

[0048] The second primary-side half-bridge module includes an upper primary-side switch Q21, a lower primary-side switch Q22, an upper voltage divider capacitor C21, a lower voltage divider capacitor C22, and a buffer capacitor C2. The upper and lower primary-side switches Q21 and Q22 are connected in series to form the second primary-side half-bridge arm. The upper and lower primary-side switches Q21 and Q22 are complementary, conducting with a 50% duty cycle. The upper and lower voltage divider capacitors C21 and C22 are connected in series to form the second voltage divider branch. The branch is connected in parallel with the second primary half-bridge arm. The high end of the second primary half-bridge arm is connected to the AC power live wire terminal L2, the low end of the second primary half-bridge arm is connected to the AC power neutral wire terminal N, the midpoint of the second primary half-bridge arm is connected to the first end of the primary winding of transformer Tr2, the midpoint of the second voltage divider branch is connected to the second end of the primary winding of transformer Tr2, and the buffer capacitor C2 is connected in parallel with the second primary half-bridge arm.

[0049] The third primary-side half-bridge module includes an upper primary-side switch Q31, a lower primary-side switch Q32, an upper voltage divider capacitor C31, a lower voltage divider capacitor C32, and a buffer capacitor C3. The upper and lower primary-side switches Q31 and Q32 are connected in series to form the third primary-side half-bridge arm. The upper and lower primary-side switches Q31 and Q32 are complementary, conducting with a 50% duty cycle. The upper and lower voltage divider capacitors C31 and C32 are connected in series to form the third voltage divider branch. The branch circuit is connected in parallel with the third primary-side half-bridge arm. The high end of the third primary-side half-bridge arm is connected to the AC power supply live wire terminal L3, and the low end is connected to the AC power supply neutral wire terminal N. The midpoint of the third primary-side half-bridge arm is connected to the first terminal of the primary winding of transformer Tr3. The midpoint of the third voltage divider branch is connected to the third terminal of the primary winding of transformer Tr3. The buffer capacitor C3 is connected in parallel with the third primary-side half-bridge arm. The aforementioned primary-side upper and lower switching transistors can be bidirectional gallium nitride (GaN) switching devices.

[0050] The secondary half-bridge module includes three secondary half-bridge arms and a common half-bridge arm. The first end of the secondary winding of each transformer is connected to the midpoint of the arm of a secondary half-bridge arm, and the second end of the secondary winding of each transformer is connected to the midpoint of the arm of the common half-bridge arm. The high-end of the three secondary half-bridge arms is connected to the high-end of the arm of the common half-bridge arm, and the low-end of the three secondary half-bridge arms is connected to the low-end of the arm of the common half-bridge arm.

[0051] Specifically, the first secondary half-bridge arm includes a secondary upper switch Q15 and a secondary lower switch Q16. The secondary upper switch Q15 and the secondary lower switch Q16 are connected in series to form the first secondary half-bridge arm. The secondary upper switch Q15 and the secondary lower switch Q16 are complementary in conducting with a 50% duty cycle.

[0052] The second secondary half-bridge arm includes an upper secondary switch Q25 and a lower secondary switch Q26. The upper secondary switch Q25 and the lower secondary switch Q26 are connected in series to form the second secondary half-bridge arm. The upper secondary switch Q25 and the lower secondary switch Q26 are complementary in conducting with a 50% duty cycle.

[0053] The third secondary half-bridge arm includes the upper secondary switch Q35 and the lower secondary switch Q36. The upper secondary switch Q35 and the lower secondary switch Q36 are connected in series to form the third secondary half-bridge arm. The upper secondary switch Q35 and the lower secondary switch Q36 are complementary in conducting with a 50% duty cycle.

[0054] The common half-bridge arm includes a common upper switch Q7 and a common lower switch Q8, which are connected in series to form the common half-bridge arm. The common upper switch Q7 and the common lower switch Q8 are complementary in conducting with a 50% duty cycle. The secondary half-bridge module includes an output filter capacitor Co, and the common half-bridge arm is connected in parallel with the output filter capacitor Co.

[0055] The three-phase single-stage converter circuit also includes an input switching circuit, which is connected between the primary half-bridge module and the AC power live wire. The input switching circuit is configured to either three-phase input mode or single-phase input mode.

[0056] In three-phase input mode, the high-end of the bridge arm of each of the three primary-side half-bridge modules is connected to the three different live wire terminals of the three-phase AC power supply.

[0057] In single-phase input mode, the high-end of the bridge arms of the three primary-side half-bridge modules are connected to the same live wire terminal of the single-phase AC power supply.

[0058] Specifically, the switching circuit includes a single-pole double-throw relay K2 and a single-pole double-throw relay K3. The moving end of the single-pole double-throw relay K2 is connected to the high end of the bridge arm of at least one primary-side half-bridge module, that is, the moving end of the single-pole double-throw relay K2 is connected to the high end of the bridge arm of the second primary-side half-bridge module. The first stationary end of the single-pole double-throw relay K2 is connected to the AC power live wire L2, the second stationary end of the single-pole double-throw relay K2 is connected to the AC power live wire L1, and the second stationary end of the single-pole double-throw relay K2 is also connected to the high end of the bridge arm of the first primary-side half-bridge module.

[0059] The moving end of the single-pole double-throw relay K3 is connected to the high end of the third primary side half-bridge arm. The first stationary end of the single-pole double-throw relay K3 is connected to the AC power live wire L3. The second stationary end of the single-pole double-throw relay K3 is connected to the AC power live wire L1. The second stationary end of the single-pole double-throw relay K3 is also connected to the high end of the first primary side half-bridge arm.

[0060] In three-phase input mode, the first stationary terminal of the single-pole double-throw relay K2 is configured to be connected to the live wire terminal L2 of the three-phase AC power supply, and the first stationary terminal of the single-pole double-throw relay K3 is configured to be connected to the live wire terminal L3 of the three-phase AC power supply. At this time, the circuit operates in three-phase input mode.

[0061] In single-phase input mode, the second stationary terminal of the single-pole double-throw relay K2 is configured to be connected to the live wire terminal L1 of the three-phase AC power supply, and the second stationary terminal of the single-pole double-throw relay K3 is configured to be connected to the live wire terminal L1 of the three-phase AC power supply. At this time, the circuit operates in single-phase input mode.

[0062] In this embodiment, the resonant inductor Ls is located on both the primary and secondary sides of the transformer. The three-phase single-stage converter circuit includes a DC blocking capacitor connected between the secondary winding of the transformer and the midpoint of the secondary half-bridge arm. However, in other embodiments, the resonant inductor can also be located solely on the primary or secondary side of the transformer, or it can be magnetically integrated as a leakage inductor within the transformer. These modifications all achieve the purpose of this invention.

[0063] Example of a control method for a three-phase single-stage converter circuit: The control method for a three-phase single-stage converter circuit includes the following steps. Reference Figure 4 The first primary-side half-bridge module includes a primary-side upper switch Q11 and a primary-side lower switch Q12. The primary-side upper switch Q11 and the primary-side lower switch Q12 are connected in series to form the first primary-side half-bridge arm. The primary-side upper switch Q11 and the primary-side lower switch Q12 are complementary in conducting with a 50% duty cycle.

[0064] The second primary-side half-bridge module includes a primary-side upper switch Q21 and a primary-side lower switch Q22. The primary-side upper switch Q21 and the primary-side lower switch Q22 are connected in series to form the second primary-side half-bridge arm. The primary-side upper switch Q21 and the primary-side lower switch Q22 are complementary in conducting with a 50% duty cycle.

[0065] The third primary-side half-bridge module includes primary-side upper switch Q31 and primary-side lower switch Q32. The primary-side upper switch Q31 and primary-side lower switch Q32 are connected in series to form the third primary-side half-bridge arm. The primary-side upper switch Q31 and primary-side lower switch Q32 are complementary in conducting with a 50% duty cycle.

[0066] The first secondary half-bridge arm includes an upper secondary switch Q15 and a lower secondary switch Q16. The upper secondary switch Q15 and the lower secondary switch Q16 are connected in series to form the first secondary half-bridge arm. The upper secondary switch Q15 and the lower secondary switch Q16 are complementary in conducting with a 50% duty cycle. The high end and low end of the first secondary half-bridge arm are used to connect to a DC power supply.

[0067] The second secondary half-bridge arm includes an upper secondary switch Q25 and a lower secondary switch Q26. The upper secondary switch Q25 and the lower secondary switch Q26 are connected in series to form the second secondary half-bridge arm. The upper secondary switch Q25 and the lower secondary switch Q26 are complementary in conducting with a 50% duty cycle. The high-end and low-end of the second secondary half-bridge arm are used to connect to the DC power supply.

[0068] The third secondary half-bridge arm includes an upper secondary switch Q35 and a lower secondary switch Q36. The upper secondary switch Q35 and the lower secondary switch Q36 are connected in series to form the third secondary half-bridge arm. The upper secondary switch Q35 and the lower secondary switch Q36 are complementary in conducting with a 50% duty cycle. The high end and low end of the third secondary half-bridge arm are used to connect to the DC power supply.

[0069] The common half-bridge arm includes a common upper switch Q7 and a common lower switch Q8. The common upper switch Q7 and the common lower switch Q8 are connected in series to form a common secondary side arm. The common upper switch Q7 and the common lower switch Q8 are complementary in conduction with a 50% duty cycle. The high end and low end of the common secondary side arm are used to connect to the DC power supply.

[0070] There is a phase difference φ1 (outer phase shift angle) between the common upper switch Q7 and the primary side upper switch Q11, and a phase difference α1 (inner phase shift angle) between the common upper switch Q7 and the secondary side lower switch Q16. The range of φ1 is -π / 2 to π / 2, and the range of α1 is 0 to π. By controlling φ1 and α1 in a certain way, the power factor control of the AC input terminal of L1 phase and the precise control of the DC output current can be achieved simultaneously.

[0071] There is a phase difference φ2 (outer phase shift angle) between the common upper switch Q7 and the primary side upper switch Q21, and a phase difference α2 (inner phase shift angle) between the common upper switch Q7 and the secondary side lower switch Q26. The range of φ2 is -π / 2 to π / 2, and the range of α2 is 0 to π. By controlling φ2 and α2 in a certain way, the power factor control of the AC input terminal of L1 phase and the precise control of the DC output current can be achieved simultaneously.

[0072] There is a phase difference φ3 (outer phase shift angle) between the common upper switch Q7 and the primary side upper switch Q31, and a phase difference α3 (inner phase shift angle) between the common upper switch Q7 and the secondary side lower switch Q36. The range of φ3 is -π / 2 to π / 2, and the range of α3 is 0 to π. By controlling φ3 and α3 in a certain way, the power factor control of the AC input terminal of L1 phase and the precise control of the DC output current can be achieved simultaneously.

[0073] Users can also independently set each external phase shift angle (φ) and internal phase shift angle (α) according to actual needs, and can simultaneously and accurately control the power factor at the input end and the current at the output end of the phase. Although the three-phase secondary side shares a bridge arm in hardware, thanks to the decoupling control strategy, the three phases can achieve completely independent power regulation without interfering with each other.

[0074] Power supply equipment example: The power supply equipment includes the three-phase single-stage conversion circuit of the above scheme. The power supply equipment can be, but is not limited to, on-board charger, on-board power supply, inverter, charging pile system or charging equipment.

[0075] Example of a means of transportation: The transportation vehicles include the three-phase single-stage conversion circuit of the above scheme, and the transportation vehicles can be new energy electric cars, new energy electric buses, new energy electric freight trucks, new energy electric cleaning vehicles, new energy electric rail transit vehicles, new energy electric air vehicles, new energy electric shipping vehicles, etc.

[0076] Of course, the above embodiments are only preferred embodiments of this case. In specific applications, the primary-side switching transistors in the above embodiments use bidirectional GaN devices, which can also be replaced by other forms of bidirectional switches, such as a bidirectional switch formed by two unidirectional switches connected back-to-back in series. Besides being a primary-side half-bridge module, the primary-side bridge module can also be a primary-side full-bridge module. That is, if a higher power conversion requirement is to be handled, a module such as... Figure 1 The full-bridge alternative to a can also achieve the purpose of this case.

[0077] As can be seen from the above, this solution reduces the total number of switching transistors from 18 in the traditional solution to 14 by designing the secondary side of the three-phase converter circuit as a shared structure of three independent half-bridge arms and one common half-bridge arm. This not only directly reduces the cost of components, but also greatly simplifies the PCB layout and drive circuit design, effectively improves the power density and reliability of the system, and achieves the core objective of simplifying the circuit structure.

Claims

1. A three-phase single-stage converter circuit, characterized in that, It includes three primary-side bridge modules, three transformers, and a secondary-side half-bridge module; The midpoint of the bridge arm of each primary-side bridge module is connected to the primary winding of a transformer, the high end of the bridge arm of each primary-side bridge module is connected to the live wire of the AC power supply, and the low end of the bridge arm of each primary-side bridge module is connected to the neutral wire of the AC power supply. The secondary half-bridge module includes three secondary half-bridge arms and a common half-bridge arm. The first end of the secondary winding of each transformer is connected to the midpoint of the arm of one of the secondary half-bridge arms, and the second end of the secondary winding of each transformer is connected to the midpoint of the arm of the common half-bridge arm. The high ends of the three secondary side half-bridge arms are connected to the high ends of the common half-bridge arm, and the low ends of the three secondary side half-bridge arms are connected to the low ends of the common half-bridge arm.

2. The three-phase single-stage converter circuit according to claim 1, characterized in that: The primary side bridge module is a primary side half bridge module.

3. The three-phase single-stage converter circuit according to claim 2, characterized in that: The primary-side half-bridge module includes an upper primary-side switch, a lower primary-side switch, an upper voltage divider capacitor, and a lower voltage divider capacitor. The upper and lower primary-side switches are connected in series to form a primary-side half-bridge arm, and the upper and lower voltage divider capacitors are connected in series to form a voltage divider branch. The voltage divider branch is connected in parallel with the primary-side half-bridge arm.

4. The three-phase single-stage converter circuit according to claim 3, characterized in that: The high end of the primary half-bridge arm is connected to the live wire of the AC power supply, the low end of the primary half-bridge arm is connected to the neutral wire of the AC power supply, the midpoint of the primary half-bridge arm is connected to the first end of the primary winding of the transformer, and the midpoint of the voltage divider branch is connected to the second end of the primary winding of the transformer.

5. The three-phase single-stage converter circuit according to claim 4, characterized in that: The primary-side half-bridge module includes a buffer capacitor, which is connected in parallel with the primary-side half-bridge arm.

6. The three-phase single-stage converter circuit according to claim 1, characterized in that: The secondary half-bridge module includes an output filter capacitor, and the common half-bridge arm is connected in parallel with the output filter capacitor.

7. The three-phase single-stage converter circuit according to claim 1, characterized in that: The primary resonant inductance of the transformer is located on one side of the primary winding of the transformer.

8. The three-phase single-stage converter circuit according to claim 1, characterized in that: The secondary resonant inductance of the transformer is located on one side of the secondary winding of the transformer.

9. The three-phase single-stage converter circuit according to claim 1, characterized in that: The three-phase single-stage converter circuit includes a DC blocking capacitor, which is connected between the secondary winding of the transformer and the midpoint of the secondary half-bridge arm.

10. The three-phase single-stage converter circuit according to claim 3, characterized in that: The primary-side upper switch and / or the primary-side lower switch are bidirectional gallium nitride switching devices.

11. The three-phase single-stage converter circuit according to any one of claims 1 to 10, characterized in that: The three-phase single-stage converter circuit also includes an input switching circuit, which is connected between the primary half-bridge module and the AC power supply live wire terminal. The input switching circuit is configured to either a three-phase input mode or a single-phase input mode. In the three-phase input mode, the high-end of the bridge arm of each of the three primary-side half-bridge modules is connected to the three different live wire terminals of the three-phase AC power supply. In the single-phase input mode, the high-end of the bridge arm of the three primary-side half-bridge modules is connected to the same live wire terminal of the single-phase AC power supply.

12. The three-phase single-stage converter circuit according to claim 11, characterized in that: The input switching circuit includes at least one single-pole double-throw relay, the moving end of which is connected to the high end of the bridge arm of at least one of the primary half-bridge modules. The first stationary terminal of the single-pole double-throw relay is configured to be connected to the corresponding live wire terminal of the three-phase AC power supply in the three-phase input mode. The second stationary terminal of the single-pole double-throw relay is configured to be connected to the same live wire terminal of the single-phase AC power supply, together with the high-end of the bridge arm of the remaining primary-side half-bridge modules, in the single-phase input mode.

13. A power supply device, characterized in that, Includes the three-phase single-stage conversion circuit described in any one of claims 1 to 12.

14. A means of transport, characterized in that, Includes the three-phase single-stage conversion circuit described in any one of claims 1 to 12.

15. A control method applied to the three-phase single-stage converter circuit according to any one of claims 2 to 11, characterized in that: The first primary-side half-bridge module includes a primary-side upper switch Q11 and a primary-side lower switch Q12. The primary-side upper switch Q11 and the primary-side lower switch Q12 are connected in series to form the first primary-side half-bridge arm. The primary-side upper switch Q11 and the primary-side lower switch Q12 are complementary in conducting with a 50% duty cycle. The second primary-side half-bridge module includes a primary-side upper switch Q21 and a primary-side lower switch Q22. The primary-side upper switch Q21 and the primary-side lower switch Q22 are connected in series to form the second primary-side half-bridge arm. The primary-side upper switch Q21 and the primary-side lower switch Q22 are complementary and conduct with a 50% duty cycle. The third primary-side half-bridge module includes a primary-side upper switch Q31 and a primary-side lower switch Q32. The primary-side upper switch Q31 and the primary-side lower switch Q32 are connected in series to form the third primary-side half-bridge arm. The primary-side upper switch Q31 and the primary-side lower switch Q32 are complementary and conduct with a 50% duty cycle. The first secondary half-bridge arm includes a secondary upper switch Q15 and a secondary lower switch Q16. The secondary upper switch Q15 and the secondary lower switch Q16 are connected in series to form the first secondary half-bridge arm. The secondary upper switch Q15 and the secondary lower switch Q16 are complementary in conduction with a 50% duty cycle. The second secondary half-bridge arm includes an upper secondary switch Q25 and a lower secondary switch Q26. The upper secondary switch Q25 and the lower secondary switch Q26 are connected in series to form the second secondary half-bridge arm. The upper secondary switch Q25 and the lower secondary switch Q26 are complementary in conduction with a 50% duty cycle. The third secondary half-bridge arm includes an upper secondary switch Q35 and a lower secondary switch Q36. The upper secondary switch Q35 and the lower secondary switch Q36 are connected in series to form the third secondary half-bridge arm. The upper secondary switch Q35 and the lower secondary switch Q36 are complementary in conduction with a 50% duty cycle. The common half-bridge arm includes a common upper switch Q7 and a common lower switch Q8. The common upper switch Q7 and the common lower switch Q8 are connected in series to form a common secondary side arm. The common upper switch Q7 and the common lower switch Q8 are complementary in conduction with a 50% duty cycle. There is a phase difference φ1 between the common upper switch Q7 and the primary side upper switch Q11, and a phase difference α1 between the common upper switch Q7 and the secondary side lower switch Q16; There is a phase difference φ2 between the common upper switch Q7 and the primary side upper switch Q21, and a phase difference α2 between the common upper switch Q7 and the secondary side lower switch Q26; There is a phase difference φ3 between the common upper switch Q7 and the primary side upper switch Q31, and there is a phase difference α3 between the common upper switch Q7 and the secondary side lower switch Q36.

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